Cougar, it sounds like your problems all stem from the fuel tank being below and far from the engine. My thought is to try an electric fuel pump but then you'll need a way to regulate pressure to the carb. Another thing to consider is the Saito pump system. You'll need a special valve Saito has and two taps in the rear cover plate with check valves. One for "in" and one for "out". With this, it'll pressurized the tank like YS does. You can read more about it in the link (#4).
http://saito-engines.info/pumps.html
